Well did a topoff today to check accuracy and scanguage was showing a lil under and had to correct it. was showing 3.6 gallons used and i pumped 3.8. mileage figured 34.23 mpg.

going to nostalgia car show/race tommorrow so will put about 200-250 mile on and since i'll be back in town will wait for low fuel light to check a full fillup. i don't have a gps so i'll have to just use the proper refill and correct it. correction worked out to 5.5% which is about inline with mileage i figured.

I'm having a very difficult time doing this calibration, mainly due to the fact that the scangauge keeps "locking up" every so often... this requires me to unplug it and then plug it back in. I've yet to go through a tank without this happening, so I lose all tank data.

Matt - so yours is locking up too huh - I find that if you shut off the ignition after being on for a time too short for the SG to communicate then it hangs and sometimes when changing the menu and then turning off the ignition screws it up too. Then it just hangs for no reason but I don't think it affects the fuel used total calculation just that it indicates that it was disconnected.

I stopped playing with the fill up adjustment after the first 9% correction was made because it kept messing with the instant MPG reading plus with the pump error we all know about who is to say what we actually are getting. The speed adjustment is still bang on with the GPS so that will stay at 3% until my tires wear down more but it probably could go up a little since it doesn't jump to the next MPH digit at .5mph over. So I am loosing a little of the fractional mph by rounding down all the time.

Matt - so yours is locking up too huh - I find that if you shut off the ignition after being on for a time too short for the SG to communicate then it hangs and sometimes when changing the menu and then turning off the ignition screws it up too. Then it just hangs for no reason but I don't think it affects the fuel used total calculation just that it indicates that it was disconnected.

I stopped playing with the fill up adjustment after the first 9% correction was made because it kept messing with the instant MPG reading plus with the pump error we all know about who is to say what we actually are getting. The speed adjustment is still bang on with the GPS so that will stay at 3% until my tires wear down more but it probably could go up a little since it doesn't jump to the next MPH digit at .5mph over. So I am loosing a little of the fractional mph by rounding down all the time.

ScanGauge is amazing because of conformance to the OBDII specification, but I'll bet that all these computers have "personalities" of implementation that lead to these quirks. From the POV of a programmer, I would say that alot of the things done at this site would void the warranty, or at least give the telephone support person fits. Also, I would think that the SG would be least reliable with newer cars like the Fit, because it's doubtfull that the SG has been *tested* against the newer cars.

For me the SG will always be a relative barometer of performance. Pick a set of rules for using your SG and stick with them.

a) calibrate the speed - you want this to match
b) leave the fillup adjustment at zero for about 5 fills/partial fills.
c) fill at the same pump/same direction, yada yada
d) keep a record of each tank as Scanguage shows it, distance, fuel used and mpg
e) after 5 fills - compare the actual receipts against the Scanguage totals - and if required, adjust as required to match the 'percentage of variance'

When I first posted this thread, it was partly due to the frustration of having adjusted the fillup based on a single result, and then seeing it needing to be adjusted again the next time, etc...

Now after 5 fills - I can see a trend - a real difference - and I will make a one time adjustment. I've also since learned that OBDII verus CANBUS in my car yield different results. OBDII is doing it off of sensors, so it is a reasonable estimation... most importantly - it is consistent...

I think the manual could be expanded a bit to help articulate these things clearer... none-the-less, I'm very pleased with it.

Interesting . . . Any thoughts on the injector operation when engine braking - some say the fuel is cut off and the SG will show it still injecting fuel . . . I see at higher revs as much at 0.5 - 0.6gph being injected with no throttle.

Well my fillup a couple days ago showed that slow pumping at this particular station Somerset pump #3 yielded very close gallons to what the SG said I used . . . SG 9.6 gallons - pump 9.678 gallons full. I need to get back to the Dartmouth pump #8 again. Be nice to have a clear filler hose going to the tank to see the fuel level as it comes up to the filler nozzle.